The ABCya website has lots of free games for math, language arts, science, social studies, typing, art, and music plus some free printable pages that change with the season. The age range for games and printables varies from prekindergarten through at least sixth grade.
The games have many different formats, but most of them are relatively simple and can be played in a short time. Many of them allow students to compete (anonymously) with other students or against a computer program.
Players can search for games under different categories: grade level, subject area, and theme. The subject areas are weighted most heavily with games for math and language arts.
The website has spaces for ads, although no ads appeared while I reviewed a number of the games. A premium subscription option offers ad-free access and the ability to play the games on mobile devices (up to five devices).